Researchers at Joslin Diabetes Center have shown that while a type of "good" fat found in the body can be activated by cold temperatures, it is not able to be activated by the drug ephedrine. The finding, published in a recent issue of Proceedings of the National Academy of Sciences, may lead to drugs or other methods aimed at activating the good fat, known as brown fat. When activated, brown fat burns calories and can help in the battle against obesity.